4. Loss to follow‐up (attrition, missing data).

Study	Number of randomised participants	Number lost to follow‐up (%)	Number lost to follow‐up Cerebrolysin/Cortexin	Number analysed by authors Cerebrolysin/Cortexin (denominator observed case)	Number lost to follow‐up Placebo	Number analysed by authors Placebo (denominator observed case)
Amiri Nikpour 2014	46	0 (0)*	0 (0)	23	0 (0)	23
CASTA 2012	1070	162 (15)	66 + 2 (premature discontinuation) = 68	461	93 + 1 (no treatment) = 94	447
CERE‐LYSE‐1 2012	119	19 (16)	11	49	8	51
Ladurner 2005	146	12 (8)	3	75	9	59
Skvortsova 2004	36	0 (0)*	0 (0)	24	0 (0)	12
Cortexin‐Shamalov 2014	272	0 (0)*	0 (0)	208	0 (0)	64
Xue 2016	84	24 (29)	n/a	n/a	n/a	n/a

*Number lost to follow‐up not stated; we assumed the value to be '0'.